Quality of Beaver Lake makes water treatment less costly, chief says

It takes about 15 hours for water to move from Beaver Lake through the treatment facility.

Beaver Lake water is relatively clean, said Larry Lloyd, chief operating officer of Beaver Water District. This allows the district to use conventional water treatment methods that keep costs down.

It takes about 15 hours for water to move from the lake through the treatment facility, Lloyd said.

Water is pumped about two miles from the intake facility on Beaver Lake to the treatment facility.

Flash mix, a 30- second mixing process, adds a coagulant to the water that causes sediment in the lake water to floc, or clump together. As the dirt in the water binds together it gets heavier and settles to the bottom of sedimentation tanks. That process brings the water to about 90 percent clean, Lloyd said

The water is filtered and sent to the clearwell, an underground tank where chlorine is added.

The pH is adjusted during treatment and again before the water is pumped to the cities.

“We get the pH to a level that won’t corrode the plumbing in your house,” Lloyd said.

The exact formulas for treating the water changes daily. Water runoff or seasonal turnover of colder water in the lake affects what the plant does to clean the water.

“The lake is dynamic,” Lloyd said.

For a couple of weeks every year taste can be off a little as the lake “turns.” The top 10 to 20 feet of the lake is warmer and filled with oxygen. The change of seasons in the spring and fall mixes the lake, setting off algae growth. The water is still safe to drink, but the algae that was there flavors the water, Lloyd said.

“If there’s 2 1/2 gallons of algae in Beaver Lake you’d still be able to taste it,” he said.

Benton Washington Regional Public Water Authority uses an almost identical process to treat lake water sold to rural customers.

Water conservation is important, said Tim Nyander, Fayetteville utilities director.

“All the water that we have on this planet is all we’re ever going to get,” he said, pointing to the water cycle. “We can’t produce more.”